"Chen, Tim C" <tim.c.c...@intel.com> writes:
>>So this is impossible without THP swapin. While 2M swapout makes a lot of
>>sense, I doubt 2M swapin is really useful. What kind of application is
>>to do sequential memory access?
Anything that touches regions larger than 4K and we want to do the
kernel do minimal work to manage the swapping.
> We waste a lot of cpu cycles to re-compact 4K pages back to a large page
> under THP. Swapping it back in as a single large page can avoid
> fragmentation and this overhead.
Also splitting something just to merge it again is wasteful.
A lot of big improvements in the block and VM and network layers
over the years came from avoiding that kind of wasteful work.